The present invention relates generally to a push-button type tuning apparatuses, and more particularly to a push-button tuning apparatus wherein improved tuning accuracy and a pleasant touch sensation in the pushing operation are attained by eliminating play from the push-button.
In general, a push-button type tuning apparatus is constructed with its push-buttons slidably fitted in support openings formed in a pair of support plates confronting each other in a frame structure and preset tuning and reset tuning (re-tuning) are performed by pushing the push-buttons. Due to the above described arrangement, however, there inevitably exists a certain amount of play between the push-button and the support openings. Accordingly, there arises a problem in that the push-button is apt to be erroneously positioned when pushed because of this play. This results in tuning error. Furthermore, the push-button is apt to wobble when being pushed and this is perceived as an unpleasant sensation by the finger.
In order to overcome the above described problems, a push-buton tuning apparatus has been proposed wherein each push-button comprises two slide plates confronting each other with a pin embedded in one slide plate fitting into a slot formed in the other slide plate, the slot being inclined with respect to the sliding direction thereof. When the push-button is pressed, the pin rides on the slope of the inclined slot forcing the slide plates to maintain contact with the upper and lower edges of the support openings. Therefore, the play in the slide plates is eliminated and the accuracy in preset and reset tuning improved accordingly. However, since each push-button has two separate plates, the tuner apparatus becomes complicated, bulky and expensive to fabricate.
There has been proposed and put into practice another push-button type tuning apparatus in which the push-button has a single plate and an auxiliary plate is fixed to at least one support plate so as to project somewhat into a support opening, thus supporting a push-rod (plate) between one edge of the support opening and one edge of the auxiliary plate in what is intended to be a play-free arrangement. However, since the auxiliary plate is a rigid body, it is difficult to eliminate play this apparatus in actual practice.